U.S. patent application number 11/980311 was filed with the patent office on 2008-05-22 for electro-optical device and electronic apparatus having the same.
This patent application is currently assigned to Seiko Epson Corporation. Invention is credited to Tomio Suzuki.
Application Number | 20080117652 11/980311 |
Document ID | / |
Family ID | 39416747 |
Filed Date | 2008-05-22 |
United States Patent
Application |
20080117652 |
Kind Code |
A1 |
Suzuki; Tomio |
May 22, 2008 |
Electro-optical device and electronic apparatus having the same
Abstract
It is provided an electro-optical device including an
electro-optical panel having a display area on which light from a
light source is incident and an optical thin film disposed on the
electro-optical panel at the side on which the light is incident
and covering at least a portion of the display area. The optical
thin film transmits at least a light component in a first
wavelength range of the light from the light source and reflects at
least a light component in a second wavelength range, wavelength in
the second wavelength range being longer than wavelength in the
first wavelength range.
Inventors: |
Suzuki; Tomio;
(Fujimi-machi, JP) |
Correspondence
Address: |
ADVANTEDGE LAW GROUP, LLC
3301 NORTH UNIVERSITY AVE., SUITE 200
PROVO
UT
84604
US
|
Assignee: |
Seiko Epson Corporation
Tokyo
JP
|
Family ID: |
39416747 |
Appl. No.: |
11/980311 |
Filed: |
October 30, 2007 |
Current U.S.
Class: |
362/622 ;
385/130 |
Current CPC
Class: |
G02F 1/133509 20130101;
G02F 2203/11 20130101; G02F 1/133385 20130101 |
Class at
Publication: |
362/622 ;
385/130 |
International
Class: |
F21V 7/04 20060101
F21V007/04; G02B 6/10 20060101 G02B006/10 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 16, 2006 |
JP |
2006-309939 |
Claims
1. An electro-optical device comprising: an electro-optical panel
including a display area on which light from a light source is
incident; and an optical thin film disposed on the electro-optical
panel at the side on which the light is incident and covering at
least a portion of the display area, wherein the optical thin film
transmits at least a light component in a first wavelength range of
the light from the light source and reflects at least a light
component in a second wavelength range, wavelength in the second
wavelength range being longer than wavelength in the first
wavelength range.
2. The electro-optical device according to claim 1, wherein the
optical thin film transmits a visible light component as the light
component in the first wavelength range and reflects an infrared
light component as the light component in the second wavelength
range.
3. The electro-optical device according to claim 1, wherein the
optical thin film is a lamination film composed of alternately
laminated zirconium oxide and silicon oxide films.
4. The electro-optical device according to claim 1, wherein the
optical thin film is a lamination film composed of alternately
laminated niobium oxide and silicon oxide films.
5. The electro-optical device according to claim 1, wherein the
electro-optical panel includes a pair of substrates having an
electro-optical material therebetween; and the optical thin film is
disposed on a surface of one of the pair of substrates, wherein the
one of the pair of substrates is at the side on which light from
the light source is incident and the surface on which the optical
thin film is disposed is at the side on which light from the light
source is incident.
6. The electro-optical device according to claim 1, wherein the
electro-optical panel includes a pair of substrates having an
electro-optical material therebetween and a pair of dust-proof
substrates disposed on the pair of substrates, respectively, at the
sides not opposing the electro-optical material; and the optical
thin film is disposed on a surface of one of the pair of dust-proof
substrates, wherein the one of the pair of dust-proof substrates is
at the side on which light from the light source is incident and
the surface on which the optical thin film is disposed is at the
side on which light from the light source is incident.
7. An electro-optical device comprising: a light source emitting
light in a first wavelength range and a second wavelength range,
wavelength in the second wavelength range being longer than
wavelength in the first wavelength range an electro-optical panel
including a display area on which light from a light source is
incident; and an optical thin film disposed on the electro-optical
panel at the side on which the light is incident and covering at
least a portion of the display area, wherein the optical thin film
transmits at least a light component in a first wavelength range of
the light from the light source and reflects at least a light
component in a second wavelength range.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates to a technical field of
electro-optical devices such as liquid crystal devices and of
electronic apparatuses having the electro-optical devices, such as
liquid crystal projectors.
[0003] 2. Related Art
[0004] In a case that a liquid crystal device, which is an example
of the electro-optical devices, is used as a light valve of a
liquid crystal projector, intense light from a light source is
condensed and incident on the liquid crystal device for projecting
an enlarged image on a screen. The incidence of such intense light
from a light source raises the temperature of the liquid crystal
device and, thereby, the temperature of a liquid crystal interposed
between a pair of transparent substrates of the liquid crystal
device, resulting in deterioration of properties of the liquid
crystal. In order to solve such a problem, for example,
JP-A-8-76109 (Patent Document 1) discloses technique of preventing
a liquid crystal device from increasing in temperature due to
infrared light. That is, a mirror having a low reflectivity of
infrared light is integrated into an optical system of a liquid
crystal projector, and thereby an infrared light component is
eliminated from light incident on the liquid crystal device.
[0005] Furthermore, if dirt or dust (hereinafter simply referred to
as "dust") is adhered to the surface of a light valve, the image of
the dust is also projected on a projection screen. Therefore, the
image quality may be decreased. Consequently, many liquid crystal
devices additionally have dust-proof substrates on the outer
surfaces of substrates for the liquid crystal devices.
[0006] However, in the technique disclosed in Patent Document 1,
since a mirror having a low reflectivity of infrared light is
integrated into an optical system of a liquid crystal projector,
miniaturization of the optical system is difficult compared to that
of a liquid crystal device not having such a mirror. Thus, there is
a technical problem that miniaturization of the liquid crystal
projector is difficult. In addition, extra cost for manufacturing
such a mirror makes it difficult to decrease the manufacturing cost
of the liquid crystal projector.
SUMMARY
[0007] An advantage of some aspects of the present invention is
that an increase in temperature of an electro-optical device can be
inhibited and that thereby an electro-optical device having high
reliability and also an electronic apparatus including such an
electro-optical device are provided.
[0008] An electro-optical device according to the present invention
includes an electro-optical panel having a display area on which
light from a light source is incident and an optical thin film
disposed on the electro-optical panel at the side on which the
light from the light source is incident. The optical thin film
covers at least a portion of the display area, and transmits at
least a light component in a first wavelength range of the light
from the light source and reflects at least a light component in a
second wavelength range, wavelength in the second wavelength range
is longer than wavelength in the first wavelength range.
[0009] In the electro-optical device according to the present
invention, the electro-optical panel is composed of, for example, a
pair of substrates and an electro-optical material, such as a
liquid crystal, interposed between the pair of substrates. In the
operation of the electro-optical panel, light, such as white light,
from a light source, such as a halogen lamp, is incident on the
display area of the electro-optical panel. The light thus entered
the electro-optical panel is modulated by the electro-optical
material such as a liquid crystal according to, for example, an
image signal and is projected by transmission or reflection as
projection light. Then, image display in the display area is
performed. An example of such electro-optical devices is a liquid
crystal device which is used as a light valve of a projection-type
display apparatus.
[0010] In the present invention, particularly, an optical thin film
is disposed on the electro-optical panel at the side on which light
from a light source is incident so as to partially cover at least
the display area. The optical thin film transmits at least a light
component in a first wavelength range of the light from the light
source and reflects at least a light component in a second
wavelength range longer than the first wavelength range. The "light
component in a first wavelength range" according to the present
invention is typically a visible light component and contributes to
image display by the electro-optical device. The "light component
in a second wavelength range" according to the present invention is
typically an infrared light component and does not contribute to
image display by the electro-optical device. The optical thin film
is typically disposed on the outermost surface of the
electro-optical panel at the side on which light from a light
source is incident and covers the display area. The optical thin
film is formed of, for example, a lamination film of a plurality of
transparent insulating films or conducting films having different
refractive indices. The refractive indices, film thicknesses, the
order of lamination, and the like of the plurality of transparent
insulating films or conducting films are properly determined
depending on the first and the second wavelength ranges.
Furthermore, the optical thin film is not limited to a lamination
film and may be formed as a single layer film or a single film.
[0011] Since the optical thin film transmits a light component,
which is typically a visible light component, in the first
wavelength range of the light from a light source, the image
display in the display area can be reliably performed. In addition,
since the optical thin film reflects a light component, which is
typically an infrared light component, in the second wavelength
range of the light from the light source, an increase in
temperature of the electro-optical panel can be inhibited or
decreased. In other words, by the optical thin film, the light
component in the first wavelength range, which contributes to image
display, can be reliably incident on the electro-optical panel,
while the light component in the second wavelength range, which may
cause an increase in temperature of the electro-optical panel and
does not contribute to image display, is prevented from being
incident on the electro-optical panel. That is, the image display
in the electro-optical panel can be reliably performed by the light
component in the first wavelength range, while inhibiting useless
temperature increase of the electro-optical panel caused by the
light component in the second wavelength range, which does not
contribute to the image display.
[0012] As described above, in the electro-optical device according
to the present invention, the temperature increase during the
operation can be inhibited or decreased by the optical thin film
disposed on the electro-optical panel at the side on which the
light from a light source is incident. Therefore, the
electro-optical device capable of maintaining high-quality display
properties over a long period of time and having excellent
reliability can be provided.
[0013] In an electro-optical device according to an embodiment of
the present invention, the optical thin film transmits a visible
light component as the light component in the first wavelength
range and reflects an infrared light component as the light
component in the second wavelength range.
[0014] In this embodiment, the optical thin film transmits at least
a visible light component and reflects at least an infrared light
component. The term "visible light component" in the present
invention means light which can be recognized by human eyes and has
a wavelength, for example, in the range of from about 380 to about
780 nm. The term "infrared light component" in the present
invention means light having a wavelength longer than that of the
visible light component of the light from a light source and is,
for example, light having a wavelength longer than about 780 nm.
Therefore, the image display in the electro-optical panel can be
reliably performed by visible light, while inhibiting a useless
increase in temperature of the electro-optical panel due to
infrared light.
[0015] In an electro-optical device according to another embodiment
of the present invention, the optical thin film is a lamination
film composed of alternately laminated zirconium oxide and silicon
oxide films.
[0016] In this embodiment, for example, the optical thin film is a
lamination film composed of alternately laminated zirconium oxide
(ZrO.sub.2) and silicon oxide (SiO.sub.2) films in this order from
the bottom on a surface of an opposing substrate or dust-proof
substrate, composed of, for example, a quartz substrate, of the
electro-optical panel. The opposing substrate or the dust-proof
substrate is at the side on which the light from a light source is
incident, and the surface on which the optical thin film is
disposed is at the side on which the light from the light source is
incident. Therefore, by the optical thin film, at least the light
component in the first wavelength range of the light from the light
source can be reliably transmitted and at least the light component
in the second wavelength range can be reliably reflected.
[0017] Furthermore, the thickness of each zirconium oxide film and
silicon oxide film may be properly determined depending on the
first and second wavelength ranges.
[0018] In an electro-optical device according to another embodiment
of the present invention, the optical thin film is a lamination
film composed of alternately laminated niobium oxide and silicon
oxide films.
[0019] In this embodiment, the optical thin film is a lamination
film composed of alternately laminated niobium oxide
(Nb.sub.2O.sub.5) and silicon oxide films in this order from the
bottom on a surface of an opposing substrate or dust-proof
substrate, composed of, for example, a quartz substrate, of the
electro-optical panel. The opposing substrate or dust-proof
substrate is at the side on which the light from a light source is
incident, and the surface on which the optical thin film is
disposed is at the side on which the light from the light source is
incident. Therefore, by the optical thin film, at least the light
component in the first wavelength range of the light from the light
source can be reliably transmitted and at least the light component
in the second wavelength range can be reliably reflected.
[0020] In an electro-optical device according to another embodiment
of the present invention, the electro-optical panel includes a pair
of substrates having an electro-optical material therebetween, and
the optical thin film is disposed on a surface of one of the pair
of substrates. The one of the pair of substrates is at the side on
which the light is incident, and the surface on which the optical
thin film is disposed is at the side on which light is
incident.
[0021] In this embodiment, the light component in the second
wavelength range can be reflected on the outermost surface of the
electro-optical panel at the side on which the light from a light
source is incident. Therefore, the temperature increase of the
electro-optical panel can be reliably inhibited or decreased.
Consequently, the deterioration of properties of the
electro-optical material such as a liquid crystal interposed
between the pair of substrates can be inhibited or prevented.
[0022] In addition, in this embodiment, the image display in the
display area is performed by, for example, applying a voltage
according to an image signal to the electro-optical material such
as a liquid crystal.
[0023] In an electro-optical device according to another embodiment
of the present invention, the electro-optical panel includes a pair
of substrates having an electro-optical material therebetween and a
pair of dust-proof substrates disposed on the pair of substrates,
respectively, at the sides not facing the electro-optical material.
The optical thin film is disposed on a surface of one of the pair
of dust-proof substrates. The one of the pair of dust-proof
substrates is at the side on which the light is incident, and the
surface on which the optical thin film is disposed is at the side
on which light is incident.
[0024] In this embodiment, the light component in the second
wavelength range can be reflected on the outermost surface of the
electro-optical panel at the side on which the light from the light
source is incident. Therefore, the temperature increase of the
electro-optical panel can be reliably inhibited or decreased. In
addition, a decrease in image quality, which is caused by that an
image of dust adhered to the pair of substrates is projected on a
projection screen, can be prevented by the transparent dust-proof
substrates composed of, for example, glass.
[0025] The electronic apparatus according to the present invention
includes an electro-optical device according to the present
invention described above, though the device is not limited to
them.
[0026] Since the electronic apparatus according to the present
invention includes the electro-optical device according to the
present invention, various electronic apparatuses, such as a
projection-type display apparatus, a mobile phone, an electronic
organizer, a word processor, a viewfinder-type video tape recorder,
a monitor-direct-view-type video tape recorder, a work station, a
video phone, a POS terminal, and a touch panel, which can perform
high-quality display and are excellent in reliability can be
achieved. Furthermore, for example, electrophoresis apparatuses
such as electronic paper can be achieved as electronic devices
according to the present invention.
[0027] These functions and other advantages of the present
invention will be apparent from the following description of
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0029] FIG. 1 is a plan view illustrating the whole structure of a
liquid crystal device according to a first embodiment of the
present invention.
[0030] FIG. 2 is a cross-sectional view taken along the line II-II
in FIG. 1.
[0031] FIG. 3 is an equivalent circuit diagram of pixels in a
liquid crystal device according to the first embodiment of the
present invention.
[0032] FIG. 4 is an enlarged cross-sectional view illustrating a
structure of an optical thin film of the liquid crystal device
according to the first embodiment of the present invention.
[0033] FIG. 5 is a cross-sectional view of a device according to a
second embodiment of the present invention and corresponds to FIG.
2 in the first embodiment.
[0034] FIG. 6 is an enlarged cross-sectional view of an optical
thin film according to a second embodiment of the present invention
and corresponds to FIG. 4 in the first embodiment.
[0035] FIG. 7 is a plan view illustrating a projector as an example
of the electronic apparatus including the electro-optical device
according to the present invention.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0036] The embodiments of the present invention will now be
described with reference to the drawings. The following embodiments
will be described using a TFT active matrix driving liquid crystal
device having a built-in driving circuit as an example of the
electro-optical device according to the present invention.
First Embodiment
[0037] A liquid crystal device according to a first embodiment will
be described with reference to FIGS. 1 to 4. First, the whole
structure of the liquid crystal device according to this embodiment
will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan
view illustrating the whole structure of the liquid crystal device
according to this embodiment, and FIG. 2 is a cross-sectional view
taken along the line II-II in FIG. 1. In FIG. 2, the individual
layers and components are drawn in different scales so that the
films and the components can be easily recognized on the
drawing.
[0038] In FIGS. 1 and 2, the liquid crystal device 110 according to
this embodiment includes a liquid crystal panel 110a and an optical
thin film 810 disposed on the surface of the liquid crystal panel
110a at the side on which light is incident. In the liquid crystal
device 110 in this embodiment, white light from a light source such
as a halogen lamp is incident on the device as incident light from
the upper side in FIG. 2.
[0039] In FIGS. 1 and 2, the liquid crystal panel 110a includes a
TFT array substrate 10 and an opposing substrate 20 which are
arranged so as to oppose each other as an example of "a pair of
substrates" according to the present invention. The TFT array
substrate 10 and the opposing substrate 20 are composed of quartz
glass substrates. Furthermore, the liquid crystal panel 110a
includes a liquid crystal layer 50 composed of a liquid crystal
interposed between the TFT array substrate 10 and the opposing
substrate 20 as an example of "an electro-optical material"
according to the present invention. The TFT array substrate 10 and
the opposing substrate 20 are bonded to each other with a sealant
52 disposed on a sealing area on the circumference of an image
display area 10a.
[0040] In FIG. 1, along the inner side of the sealing area in which
the sealant 52 is arranged, a light-shielding film frame 53 having
light-blocking effect is disposed at the side of the opposing
substrate 20 for determining the frame area of the image display
area 10a. In the periphery along the outer area of the sealing area
in which the sealant 52 is arranged, a data line driving circuit
101 and external circuit connecting terminals 102 are disposed
along one edge of the TFT array substrate 10. A sampling circuit 7
is disposed on a more inner peripheral side than the sealing area
along the one edge so as to be covered by the light-shielding film
frame 53. Scanning line driving circuits 104 are disposed on more
inner peripheral sides than the sealing area along the two other
edges extending perpendicularly from the one edge so as to be
covered by the light-shielding film frame 53. Furthermore, on the
TFT array substrate 10, vertical conducting terminals 106 for
electrically connecting between the upper and lower substrates with
vertical conductors 107 are disposed in the areas that oppose the
four corners of the opposing substrate 20. These components provide
electrical conductivity between the TFT array substrate 10 and the
opposing substrate 20.
[0041] On the TFT array substrate 10, routing wirings 90 for
electrically connecting the external circuit connecting terminals
102 to, for example, the data line driving circuit 101, the
scanning line driving circuits 104, and the vertical conducting
terminals 106 are disposed.
[0042] As shown in FIG. 2, on the TFT array substrate 10, a
laminate structure including TFTs (Thin Film Transistors) for pixel
switching as driving elements and wirings such as scanning lines
and data lines is formed. The image display area 10a is provided
with pixel electrodes 9a on a layer upper than the layer of the
TFTs for pixel switching and the wirings such as scanning lines and
data lines. Furthermore, a light-shielding film 23 is disposed on a
surface of the opposing substrate 20 at the side facing the TFT
array substrate 10. On the light-shielding film 23, an opposing
electrode 21 made of a transparent material such as ITO (Indium Tin
Oxide) is disposed so as to face a plurality of pixel electrodes
9a. The liquid crystal layer 50 is composed of one type or a
mixture of several types of nematic liquid crystals and has a
predetermined alignment between a pair of alignment films.
[0043] In addition to the data line driving circuit 101 and the
scanning line driving circuits 104, for example, an inspection
circuit or an inspection pattern that inspects quality and defects
of the liquid crystal device during manufacturing or at shipping
may be formed on the TFT array substrate 10, though they are not
shown in the drawings.
[0044] As shown in FIGS. 1 and 2, in this embodiment, dust-proof
substrates 410 and 420 are disposed on surfaces of the TFT array
substrate 10 and the opposing substrate 20, respectively, at the
sides not facing the liquid crystal layer 50. The dust-proof
substrates 410 and 420 are composed of crystal glass substrates as
in the TFT array substrate 10 and the opposing substrate 20 and are
adhered to the TFT array substrate 10 and the opposing substrate
20, respectively, with adhesion layers 710 and 720 composed of an
adhesive. Along the inner side of the sealing area in which the
sealant 52 is arranged, light-shielding film frames 415 and 425
having light-blocking effect are disposed on surfaces of the
dust-proof substrates 410 and 420, respectively, at the sides
facing the TFT array substrate 10 and the opposing substrate 20,
for determining the frame area of the image display area 10a, as in
the light-shielding film frame 53 provided on the opposing
substrate 20. The light-shielding film frames 415 and 425 are
composed of, for example, a metal film such as aluminum (Al) or
chromium (Cr).
[0045] These dust-proof substrates 410 and 420 can prevent a
decrease in image quality caused by that dust is adhered to the TFT
array substrate 10 or the opposing substrate 20 and an image of the
dust is projected on a projection screen.
[0046] As shown in FIGS. 1 and 2, an optical thin film 810 is
disposed on the surface of the liquid crystal panel 110a at the
side on which light is incident, namely, on a surface of the
dust-proof substrate 420, which is disposed at the opposing
substrate 20 side, at the side not facing the opposing substrate
20. The optical thin film 810 is formed on the almost entire
surface of the dust-proof substrate 420 so as to cover at least the
image display area 10a on which light is incident. The structure
and the effect of the optical thin film 810 are described in detail
below.
[0047] An electrical structure of pixels of the liquid crystal
device according to the present invention will be described with
reference to FIG. 3. FIG. 3 is an equivalent circuit diagram of
pixels of a liquid crystal device according to the first embodiment
of the present invention.
[0048] As shown in FIG. 3, in the image display area 10a of the
liquid crystal device 110, a plurality of scanning lines 11a and a
plurality of data lines 6a are arranged so as to cross each other
and to form pixels, which are each defined by each one of the
scanning lines 11a and the data lines 6a. Each of the pixels is
provided with a TFT 30, a pixel electrode 9a, and a storage
capacitor 70. The TFTs 30 are provided for applying data signals
S1, S2, . . . , Sn supplied through the data lines 6a to selected
pixels. Gates are connected to the scanning lines 11a, sources are
connected to the data lines 6a, and drains are connected to the
pixel electrodes 9a. The pixel electrodes 9a form liquid crystal
capacitors with the opposing electrode 21 so that input data
signals S1, S2, . . . , Sn are applied to the pixels and are
retained for a certain period of time. In each storage capacitor
70, one electrode is parallel to the pixel electrode 9a and is
connected to the drain of the TFT 30, and the other electrode is
connected to a potential-fixed capacitor wiring 400 so that the
potential becomes constant.
[0049] The liquid crystal device 110 employs a TFT active
matrix-driving system. The scanning line driving circuits 104
(refer to FIG. 1) sequentially apply scanning signals G1, G2, . . .
, Gm to the scanning lines 11a, and thereby the TFTs 30 in selected
pixel rows in the horizontal direction become ON state. The data
line driving circuit 101 (refer to FIG. 1) apply data signals S1,
S2, . . . , Sn to the selected pixel rows of which TFTs 30 are ON
via data lines 6a. On this occasion, the data signals S1, S2, . . .
, Sn may be sequentially supplied to each of the data lines 6a or
may be simultaneously supplied to a plurality of the data lines 6a
(for example, to each group of the data lines 6a). Consequently,
data signals are supplied to the pixel electrodes 9a corresponding
to the selected pixels. Since the TFT array substrate 10 is
disposed so as to oppose the substrate 20 via the liquid crystal
layer 50 (refer to FIG. 2), an electric field is selectively
applied to the liquid crystal layer 50 of each individual pixel of
the thus divided and arrayed pixels, and thereby the transmitted
light intensity between the both substrates is controlled by each
individual pixel and an image is displayed in gray scale. The data
signal retained in each pixel area is prevented from leakage by the
storage capacitor 70.
[0050] The structure and effect of the optical thin film of the
liquid crystal device according to the present invention will now
be specifically described with reference to FIGS. 1, 2, and 4. FIG.
4 is an enlarged cross-sectional view illustrating a specific
structure of an optical thin film of the liquid crystal device
according to this embodiment.
[0051] In this embodiment, an optical thin film 810 shown in FIG. 4
is employed. As described above with reference to FIGS. 1 and 2,
the optical thin film 810 is disposed on a surface of the
dust-proof substrate 420, which is disposed at the opposing
substrate 20 side, at the side not facing the opposing substrate 20
and covers at least the image display area 10a on which light is
incident. The optical thin film 810 is a lamination film formed by
laminating a zirconium oxide film 811 composed of zirconium oxide
(ZrO.sub.2) and a silicon oxide film 812 composed of silicon oxide
(SiO.sub.2) in this order on the dust-proof substrate 420 composed
of quartz glass. Furthermore, the thicknesses of the zirconium
oxide film 811 and the silicon oxide film 812 of the optical thin
film 810 are controlled so that the optical thin film 810 transmits
a visible light component in the wavelength range of from about 380
nm to about 780 nm of incident light and reflects an infrared light
component having a wavelength longer than about 780 nm. In other
words, by controlling each thickness of the zirconium oxide film
811 and the silicon oxide film 812, with respect to the visible
light component of incident light, each interface-reflected light
is canceled to each other at the interface between the outside
(typically, air) and the silicon oxide film 812, at the interface
between the silicon oxide film 812 and the zirconium oxide film
811, and at the interface between the zirconium oxide film 811 and
the dust-proof substrate 420. As a result, the reflection of the
visible light by the optical thin film 810 is decreased or
prevented and thereby the transmissivity of the visible light is
increased. With respect to the infrared light component of the
incident light, each interface-reflected light is enhanced to each
other at each interface, and as a result, the reflection of the
infrared light by the optical thin film 810 is increased and
thereby the transmissivity of the infrared light is decreased.
[0052] Therefore, since the visible light component of incident
light is transmitted by the optical thin film 810 and enters the
image display area 10a of the liquid crystal panel 110a, the image
display can be reliably performed in the image display area 10a. In
addition, since the infrared light component of the incident light
is reflected by the optical thin film 810 and does not enter the
image display area 10a of the liquid crystal panel 110a, the
temperature increase of the liquid crystal panel 110a can be
inhibited or decreased. In other words, by the optical thin film
810, the visible light component, which contributes to image
display, can reliably incident on the liquid crystal panel 110a,
while the infrared light component, which may cause an increase in
temperature of the liquid crystal panel 110a and does not
contribute to image display, is prevented from being incident on
the liquid crystal panel 110a. That is, the image display in the
liquid crystal panel 110a can be reliably performed by the visible
light component, while inhibiting useless temperature increase of
the liquid crystal panel 110a caused by the infrared light
component, which does not contribute to the image display.
[0053] Since useless temperature increase of the liquid crystal
panel 110a can be inhibited, the deterioration of properties of the
liquid crystal constituting the liquid crystal layer 50 of the
liquid crystal panel 110a can be inhibited or prevented. Therefore,
the liquid crystal panel 110a can maintain high-quality display
properties over a long period of time. That is, the life time as an
apparatus can be improved.
[0054] In this embodiment, the optical thin film 810 is a two-layer
film formed by laminating a single zirconium oxide film 811 and a
single silicon oxide film 812 in this order. However, the optical
thin film 810 may be a multi-layer film having a multi-layer
structure composed of more than two layers, such as a four-layer or
six-layer film, composed of alternately laminated zirconium oxide
and silicon oxide films in this order. In such a case, thicknesses
of the zirconium oxide films and the silicon oxide films can be
controlled in many kinds of combination of the thicknesses compared
to the case of a two-layer film. Therefore, the optical thin film
can transmit a visible light component and reflect an infrared
light component with higher accuracy. However, a two-layer film as
in this embodiment is preferred from the viewpoint of reducing the
manufacturing cost for the optical thin film.
[0055] Furthermore, since the liquid crystal device 110 is provided
with such an optical thin film 810, it is not required to integrate
a "mirror having a low reflectivity of infrared light" into an
optical system of a liquid crystal projector as in the technique
disclosed in the above-mentioned Patent Document 1 by using the
liquid crystal device 110 as a light valve of the liquid crystal
projector. In other words, in the liquid crystal device 110, since
the optical thin film 810, which is smaller in size compared to the
mirror, can inhibit an increase in temperature of the liquid
crystal panel 110a, the liquid crystal projector can be reduced in
size and, further, can be reduced in manufacturing cost.
[0056] As described above, in the liquid crystal device 110
according to this embodiment, an increase in temperature during the
operation can be inhibited or decreased by the optical thin film
810 disposed on the liquid crystal panel 110a at the side on which
light is incident. Therefore, the high-quality display properties
can be maintained over a long period of time, and excellent
reliability can be achieved.
Second Embodiment
[0057] A liquid crystal device according to a second embodiment
will now be described with reference to FIGS. 5 and 6. FIG. 5 is a
cross-sectional view of a device according to a second embodiment
and corresponds to FIG. 2 in the first embodiment, and FIG. 6 is an
enlarged cross-sectional view of an optical thin film according to
the second embodiment and corresponds to FIG. 4 in the first
embodiment. In FIGS. 5 and 6, the same reference numerals as those
in FIGS. 1 to 4 are used for components similar to those in the
first embodiment, and their description is optionally omitted.
[0058] The structure of the liquid crystal device 120 according to
the second embodiment shown in FIG. 5 is almost the same as that of
the liquid crystal device 110 according to the first embodiment
except that a liquid crystal panel 120a instead of the liquid
crystal panel 110a in the first embodiment and an optical thin film
820 instead of the optical thin film 810 in the first embodiment
are used.
[0059] The structure of the liquid crystal panel 120a is almost the
same as that of the liquid crystal panel 110a in the first
embodiment except that the dust-proof substrates 410 and 420
provided to the liquid crystal panel 110a in the first embodiment
are not provided (consequently, the light-shielding film frames 415
and 425 and the adhesion layers 710 and 720 are also not
provided).
[0060] In this embodiment, an optical thin film 820 shown in FIG. 5
is employed. The optical thin film 820 is disposed on the surface
of the liquid crystal panel 120a at the side on which light is
incident, namely, on the surface, not facing the liquid crystal
layer 50, of the opposing substrate 20. The optical thin film 820
is formed on the almost entire surface of the opposing substrate 20
so as to cover at least the image display area 10a on which light
is incident.
[0061] As shown in FIG. 6, the optical thin film 820 is a
lamination film formed by laminating a niobium oxide film 821, a
silicon oxide film 822, a niobium oxide film 823, and a silicon
oxide film 824 in this order on the opposing substrate 20 composed
of quartz glass. The niobium oxide films 821 and 823 are composed
of niobium oxide (Nb.sub.2O.sub.5), and the silicon oxide films 822
and 824 are composed of silicon oxide (SiO.sub.2). Furthermore, the
thicknesses of the niobium oxide films 821 and 823 and the silicon
oxide films 822 and 824 constituting the optical thin film 820 are
controlled so that the optical thin film 820 transmits a visible
light component in the wavelength range of from about 380 nm to
about 780 nm of incident light and reflects an infrared light
component having a wavelength longer than about 780 nm. In other
words, by controlling the thickness of each of the niobium oxide
films 821 and 823 and the silicon oxide films 822 and 824, with
respect to the visible light component of incident light, each
interface-reflected light is canceled to each other at the
interface between the outside (typically, air) and the silicon
oxide film 824, at the interface between silicon oxide film 824 and
the niobium oxide film 823, at the interface between the niobium
oxide film 823 and the silicon oxide film 822, at the interface
between the silicon oxide film 822 and the niobium oxide film 821,
and at the interface between the niobium oxide film 821 and the
opposing substrate 20. As a result, the reflection by the optical
thin film 820 is decreased or prevented and thereby the
transmissivity is increased. With respect to the infrared light
component of the incident light, each interface-reflected light is
enhanced to each other at each interface, and as a result, the
reflection by the optical thin film 820 is increased and thereby
the transmissivity is decreased.
[0062] Therefore, since the visible light component of incident
light is transmitted by the optical thin film 820 and enters the
image display area 10a of the liquid crystal panel 120a, the image
display in the image display area 10a can be reliably performed. In
addition, since the infrared light component of incident light is
reflected by the optical thin film 820 and does not enter the image
display area 10a of the liquid crystal panel 120a, the temperature
increase of the liquid crystal panel 120a can be inhibited or
decreased. That is, the image display in the liquid crystal panel
120a can be reliably performed by the visible light component,
while inhibiting useless temperature increase of the liquid crystal
panel 120a caused by the infrared light component, which does not
contribute to image display. In addition, since the useless
temperature increase of the liquid crystal panel 120a can be
inhibited, deterioration of properties of the liquid crystal
constituting the liquid crystal layer 50 of the liquid crystal
panel 120a can be inhibited or prevented.
[0063] In this embodiment, the optical thin film 820 is four-layer
film composed of alternately laminated niobium oxide and silicon
oxide films in this order. However, the optical thin film 820 may
be a two-layer film formed by laminating a single niobium oxide
film and a single silicon oxide film in this order or a multi-layer
film composed of more than four layers, such as a six-layer or
eight-layer film, composed of alternately laminated niobium oxide
and silicon oxide films in this order.
Electronic Apparatus
[0064] Application of the above-mentioned electro-optical devices,
namely, the liquid crystal devices, to various electronic
apparatuses will now be described. FIG. 7 is a plan view
illustrating the structure of an exemplary projector. A projector
having the liquid crystal device as a light valve will now be
described.
[0065] As shown in FIG. 7, a lamp unit 1102 including a white-light
source such as a halogen lamp is disposed inside the projector
1100. Projection light projected from this lamp unit 1102 is
separated into three primary colors of RGB by four mirrors 1106 and
two dichroic mirrors 1108 arranged in a light guide 1104 and enters
liquid crystal devices 1110R, 1110G, and 1110B serving as light
valves corresponding to the respective primary colors.
[0066] The structures of the liquid crystal devices 1110R, 1110G,
and 1110B are equivalent to that of the above-mentioned liquid
crystal device and are driven by primary color signals R, G, and B,
respectively, supplied from an image signal processing circuit. The
light modulated by these liquid crystal devices enters a dichroic
prism 1112 from three directions. In this dichroic prism 1112,
while the light beams of R and B are refracted at 90 degrees, the
light beam of G goes straight. Therefore, as a result of synthesis
of images of the individual colors, a color image is projected on a
screen or the like via a projection lens 1114.
[0067] Here, in display images by the individual liquid crystal
devices 1110R, 1110G, and 1110B, it is necessary to reverse left
and right of the display image by the liquid crystal device 1110G
with respect to the display images by the liquid crystal devices
1110R and 1110B.
[0068] Since light beams corresponding to the individual primary
colors R, G and B enter the liquid crystal devices 1110R, 1110G,
and 1110B, respectively, by means of the dichroic mirror 1108, it
is not necessary to provide a color filter.
[0069] In addition to the electronic apparatus described with
reference to FIG. 7, examples of the electronic apparatus include a
mobile-type personal computer, a mobile phone, a liquid crystal
television set, a viewfinder-type video tape recorder, a
monitor-direct-view-type video tape recorder, a car navigation
device, a pager, an electronic organizer, a calculator, a word
processor, a workstation, a video phone, a POS terminal, and a
device having a touch panel. It is needless to mention that the
present invention is applicable to these various apparatuses.
[0070] The present invention is not limited to the above-mentioned
embodiments and can be modified within in the range of the scope or
spirit which is apparent from claims and the entire description.
Electro-optical devices and electronic apparatuses having the
electro-optical devices which accompany such modifications are also
included in the technical field of the present invention.
[0071] The entire disclosure of Japanese Patent Application No.
2006-309939, filed Nov. 16, 2006 is expressly incorporated by
reference herein.
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